The present invention pertains generally to amplifiers and more particularly to isolation amplifiers used in analog computers. In the past, two different types of amplifiers have been used in an analog computer system depending upon the type of load used in conjunction with the amplifier. High gain differential amplifiers have typically been used for resistive loads while open loop variable gain amplifiers have been used in conjunction with resolver, i.e., inductive loads. These two amplifiers, however, could not be used interchangeably with the two different types of loads of the analog computer. This has required a parts inventory of amplifiers and associated circuitry of twice that which would be required if a single amplifier could be used for both resistive and inductive loads. In addition, it is desirable to have programmable gain functions provided by the amplifier rather than open loop gain adjustment as required in the amplifiers previously used in conjunction with inductive loads. To provide a single amplifier such as a differential amplifier which can be used both with resistive and inductive loads, both D.C. and A.C. feedback must be provided in the circuit design. Until now, circuitry has not been provided for the interchangeable use of a differential amplifier with both types of loads having both A.C. and D.C. feedback paths.